The WSJ reported (and I have confirmed from Japanese-language sources) that Amazon has pulled Kodansha titles from Kindle Unlimited. The service launched in Japan a couple months ago with said titles, but they are no longer available.
A fight between Amazon.com Inc. and Japanese publishers escalated Monday as the nation’s largest publisher protested the deletion of its books and magazines from Amazon Japan’s all-you-can-read subscription service.
Kodansha Inc. said more than 1,000 titles were deleted from Amazon’s Kindle Unlimited service in Japan. Kodansha called the move “one-sided” and said it didn’t believe Amazon was authorized to delete the titles.
Amazon officials in Tokyo didn’t respond to requests for comment.
Kodansha said that at first, about a dozen or so popular titles were taken down from Kindle Unlimited without notice. The publisher said that after it protested, all of the titles it had made available were deleted Friday night [Sept. 30].
Separately, an affiliate of Kodansha, Kobunsha Co., said 550 of its titles were deleted from the service.
“We don’t think Amazon is authorized to halt distribution of our titles without permission,” a Kodansha spokesman said. A spokesman for Kobunsha said the publisher’s contract with Amazon didn’t stipulate whether Amazon was allowed to take down the titles without the publisher’s permission.
The WSJ never bothers to explain why this counts as an "escalation", but I have confirmed that Kodansha issued a statement.
It's not clear what is going on here, nor do we know for certain whether Amazon removed the titles. This might be a fight between Amazon and the publishers, it might be a mistake, or it might be justified.
Amazon has removed titles from Kindle Unlimited before when it perceived that the titles were part of a page view scam, one where bots were flipping through ebooks in order to boost the number of pages read and scam Amazon out of money.
in some cases, the books belonged to innocent authors who had not participated in the scam but were swept up in the enforcement.
That could be what is happening here.
But aside from the statement, we do not know anything at this time, and so anything more would be pure speculation.